Seal for centrifugal separators



Sept. 8, 1953 G. J. sTREzYNsKl SEAL FOR CENTRIFUGAL sEpARAToRs Filed July '7, 1950 Patented Sept. 8, 19.5.3

UN ITED STAT ES T CE.

SEAL FOR CENTRIFUGAL SEPARATORS George J. Strezynski, Poughkeepsie, N Y2, as-

signor to The De Laval Separator Company, New York, N'. Y., a corporation-of New Jersey Application J ul-y 7', 1950,` Serial No. 1.7.2;59

8 Claims. 1`

This invention relates to centrifuges of the socalled closed type in which the material to be separated is supplied to the centrifugalbowl from a stationary feed pipe through a seal forming an air-tight path between the fixed pipe and an axial inlet passage of the rotary bowl. The. invention has particular reference. to an improved arrangement for feeding the material from the fixed pipe into the bowl of such centrifuges.

It is well known that. the. seal through which l the stationary feed pipe is connected to the interior of the bowl in closed centrifuges, undergoes considerable stress and wear due to the high speed at which the bowl rotates, the lateral vibra.- tional movements of the bowl incident. to its rota.- tion, and the pressure at which the feed material is usually delivered to the bowl. To relieve. such stress and wear on the seal, itv has been proposed to provide the stationary feed pipe with a nozzle extending in close proximity tov theentrance of the axial inlet passage of the bowl, sov that the feed passes. directly from the nozzle end of the pipe. into the bowl passage, as disclosed, for' example, in Forsberg Eatent No. 2,145,541. In this way, pressure energy of the feed is converted into velocity energy asi the feed` passes through the nozzle, thereby reducing the pressure of the feed on the seal.. However, while the use of such a nozzle reduces leakage and relieves the stress on the seal, it tends to impair the feeding operation by causing variations in the rate of feed to the bowl, which affect the separating operation and are therefore objectionable.

The principal .object of the present. invention is to provide a feeding arrangement for closed centrifuges, including a nozzle and seal, which overcomes the. above-noted objection. A further object is to. simplify the feeding arrangement .for such centrf'uges.

I nd that the variations in the. feed rate; when using the prior arrangement describedv above, are due to the fact that the axial feedpassage ofthe bowl moves. laterally or radially relative to the stationarz.'l feed pipe and its nozzle during rotation of the bowl. In fact, the usual mounting for the bowl allows for limited lateral movement ofthe bowl incident to its rotation. ThisY lateral movement of the. bowl causes its axial` feed passage to move out o-f direct alignment with the nozzle on the feed pipe,v thereby varying the back pres sure inthe feed pipe andthe feed rate.

According to.. the present invention, the nozzle is aligned with the axial feed passage in the bowl but extends into the. stationary feed pipe with .an annular clearance space between. the nozzle and the wall of the pipe., whereby the Ynozzle is movable Ylatetallv relative. t0. the llll A f'eXble sealing ring supports. the nozzle in alignment with the bowl passage and. forms a seal between the wall ofthe bowl passage and the wall of the' stationary feed pipe. rThe sealing ring engages the bowl around its feed passage to cause the nozzle to partake ci the. lateral. movements of. this' passage incident to rotation of the bowl. Conseqtiently,V the nozzle remains, at alltiines in accue rate augment with the axial feed passage cf the bowl, regardless of lateraldeviations of the b'owl axis relative to the feed. pipe and the other stationary structure in which the bowl rotates.

The preferred, frml of the invention is as follows; A

The sealing ring is generally Ushaped in crosssection so as, to. form annular concentric legs joined by a base portion of the ring. The inner leg constitutes a member in sealing engagement with an; axial tube proieotmg from the bowl and forming the feed passage thereof. rIhe nozzle is integral with the base portion ofv the ring, which supports the nozzle at thefreeend of the. bowl tube.y The outer leg of the ringconstitutes a flexible annular flange extending outward from JG he sealinginember and; the nozzle and forming a means for securing themto the stationary structure to provide a seal` between the wall of the stationary feed pipe and the wall of the` bowl tube.

For a better understanding of the invention, reference. mail be nad to the accompanying drawing, which; the` si glpj illustration is a vertical sectional. View 0i. a preferred form 0f the invention..

Referring to the, drawing,.- the. numeral lll desienates a centrifugal bowl adapted to be driven from the bottom (not shown). at high speed. At its upper par-t,s the bowl is' provided with a hollow tube or neck l projecting axial-'ly from the mainbedy of the bowl. The bowl is mounted in the usual manner in lower bearings (not shown) to permit` lateral movements of the'upper part of the bowl Vand th'e tube Illa through a limited rang'.

rllhe axial tube Illa forms a central feed passage Ib through which the material to be separated is delivered into.l the interior of the bowl. Radial ribs |00 are provided on the outer wall ofY the tube, around'which a sleeve Hld is closely tted. The sleeve and the ribs lc form a series of. outer passaeesiin-the tube, through which the clarified liquid is. discharged from passages Ille leading from the separating chamber of the bowl.

The bowl I is rotatable in a stationary structure having an upper part II supporting a ring I2. At its upper end, the ring I2 has an inwardly extending flange I2a surrounding the tube Illa but spaced therefrom. A cup I3 rests on top of the ange I2a and supports a sealing member I4 of rubberlike material. The member i4 is of annular form and is generally U-shaped in cross-section, the inner cylindrical portion engaging the sleeve IIJd of thebowl tube Vand the outer cylindrical portion having an annular flat ange. The cup I3 conforms generally to the shape of that part of the seal I 4 otherthan its inner tube-engaging collar portion. The seal I4 and its supporting cup I3 are clamped at their outer portions against the flange I2a. by a hollow body I5, which is drawn downward against the stationary ring l2 by a nut I6. The clarified liquid from passages Ie is discharged above the sleeve wd into a chamber a. formed by the body l5. From the chamber 15a, which is sealed at the bottom by the annular member I4, the clarified liquid is discharged through an outlet |517.

The material to be separated or clarified is fed to the bowl I0 through a stationary feed pipe il' aligned with the tube Illa. Nozzle I8 is positioned at the free end of the tube Ia. in alignment with the feed passage IIlb of the bowl. The nozzle extends into the stationary feed pipe I1, and an annular clearance space |80l is provided between the nozzle and the pipe Il. The nozzle is supported by a sealing member I9 which, as shown, is in the form of a collar closely surrounding .the tube Ia. A flexible annular ange 2o extends outward from the sealing member I9 and nozzle I8 and has a cylindrical part surrounding the member I9 in spaced relation thereto. An outwardly turned part a of the ange 20 is clamped between a shelf I5c of the body i5 and the lower end of an extension Ib of the pipe I'I. The pipe sections I1 and I'Ib` have intertting conical end portions IIc forming a tight joint. A ring nut 22 is threaded on the upper portion of the hollow body I5 and engages a shoulder Id of the pipe I'I. By tightening the nut 22, the pipe sections i'l and Hb are urged together and the ange 20 is clamped against the shelf I5c.

In the preferred form of the invention, as illustrated, the nozzle I8, sealing member I9 and fiange 2t are integral and are made of a rubberlike material, whereby the unit is exible and elastic. More particularly, the parts I9 and 20 form a flexible sealing ring which is generally U-shaped in cross-section. The sealing ring, in effect, comprises annular concentric legs I9 and 20 joined by a base portion 2l, from which the nozzle I8 extends. The nozzle I8 is of the Venturi type and has a passage I8b which tapers toward the entrance of the tube IIJa and communicates with the interior of the annular leg I5. The latter is in sealing engagement with the wall of the bowl passage Ib. The smaller end of the nozzle passage ISU is spaced somewhat above the free end of the tube Ia and is considerably smaller in diameter than the space defined by the inner leg I9.

The operation of the device is as follows: By reason of the nozzle passage Ib, the pressure energy of the material fed through the stationary pipe I'l--I'Ib is at least partly converted into velocity energy as the material passes through the nozzle. Accordingly, the pressure within the inner leg I9 is considerably reduced so as to allow a better seal between the member I9 and the wall of the bowl feed passage I0b. The member I9 not only forms part of the seal between lthe wall of passage Ib and the wall of pipe II-Ilb but also, by reason of its .engagement with tube Ilia, causes the nozzle i8 to partake of the lateral movements of passage Ib incident to rotation of the bowl. It will be apparent, therefore, that the nozzle i8 will always be accurately aligned with the bowl passage IIlb, regardless of lateral deviations of the bowl axis relative to the stationary structure including the parts II, I2, I5 and Il'. The outer leg 20, together with the clamping nut 22, constitutes the means forming a tight seal between the wall of the nozzle i8 and the wall of the stationary pipe I'I-I'Ib.

It will be apparent that the neu.r feeding arrangement is of relatively simple construction. It forms an effective and durable seal between the stationary feed pipe and the axial feed passage of the bowl and operates to effect a reduction in the pressure of the feed on the sealing member I9 without, however, impairing the uniformity of the rate at which the feed is delivered .to the bowl.

I claim:

1. In a centrifuge having a rotary centrifugal bowl and a stationary structure including a feed pipe for delivering material to the bowl, the combination of a hollow feed tube projecting axially from the bowl and rotatable therewith, the tube communicating with the interior of the bowl and being movable laterally with the bowl incident to rotation thereof, a flexible sealing member in sealing engagement with the wall of the tube, the sealing member being adapted to partake of the lateral movements of the feed tube by reason of the exiblity of said member, a nozzle member supported by said member at the free end of the tube and movable laterally with said member and the tube relative to the stationary structure, the nozzle forming between the stationary feed pipe and the tube, a passage which decreases in cross-sectional area toward the tube, and means for securing .part of the sealing member to the stationary structure in fixed relation thereto to form a seal between the wall of said pipe and the wall of the tube.

2. A combination according to claim l, in which the nozzle and the sealing member are integral and are made of flexible elastic material.

3. A combination according to claim 1, in which said means include a flexible annular flange extending outward from the sealing member and nozzle, and a clamping element for securing the outer portion of said flange to the stationary structure.

4. In a centrifuge having a rotary centrifugal bowl and a stationary structure including a feed pipe for delivering material to the bowl, the combination of a hollow feed tube projecting axially from the bowl and rotatable therewith, the tube communicating with the interior of the bowl and being movable laterally with the bowl incident to rotation thereof, a flexible sealing ring surrounding the tube and generally U-shaped in crosssection, one leg of the ring being in sealing engagement with the tube and the other leg being secured to the stationary structure, the ring having a base joining said legs, and a nozzle supported by the ring base at the free end of the tube and extending into said pipe with an annular clearance space between the nozzle and the wall of the pipe, the nozzle and said first leg being movable laterally with the tube to prevent lateral deviation of the tube relative to the nozzle.

5. In a centrifuge having a rotary centrifugal bowl and a stationary structure including a feed pipe for delivering material to the bowl, the bowl having an axial feed passage for receiving material from the feed pipe, the combination of a nozzle aligned with said passage and extending into the feed pipe with an anular clearance space between the nozzle and the wall of said pipe, the nozzle being movable laterally relative to the pipe, and a flexible ring supporting the nozzle and forming a seal between the wall of said passage and the wall of the stationary feed pipe, the ring engaging the bowl around said passage to cause the nozzle to partake of lateral movements of the lpassage incident to rotation of the bowl.

6. For use in connecting an axial feed tube of a centrifugal bowl to a stationary pipe for feeding material into said tube, a flexible sealing ring having annular concentric legs, the inner leg forming a, tube-receiving recess, the ring also having a base portion joining said legs, and a flexible nozzle integral with the ring and projecting from the base portion thereof in a direction opposite to the directions of said legs, the nozzle forming a passage communicating with said recess in the inner one of said concentric legs, said passage having at said base portion a smaller diameter than said inner leg.

7. For use in connecting an axial feecltube of a centrifugal bowl to a stationary pipe for feeding material into said tube, a flexible sealing ring having annular concentric legs, the inner leg forming a tube-receiving recess, the ring also having a base portion joining said legs, and a flexible nozzle integral with the ring and projecting from the base portion thereof in a direction opposite to the directions of said legs, the

nozzle forming a passage communicating with said recess in the inner one of said concentric legs, the passage tapering toward said tube-receiving recess and having at its tapered end the smaller diameter than said inner leg.

8. In a centrifuge having a rotary centrifugal bowl and a stationary structure including a feed pipe for delivering material to the bowl, the combination of a hollow feed tube projecting axially from the bowl and rotatable therewith, the tube communicating with the interior of the bowl and being movable laterally with the bowl incident' to rotation thereof, a flexible sealing member in sealing engagement with the wall of the tube, the sealing member being adapted to partake 0f the lateral movements of the feed tube by reason of the flexibility of said member, a nozzle supported by said member at the free end of the tube and movable laterally with said member and the tube relative to the stationary structure, the nozzle affording communication between the stationary feed pipe and the tube and projecting from the sealing member into the stationary pipe with an annular clearance space between the nozzle and said pipe to accommodate said lateral movement of the nozzle, and means for securing part of the sealing member to the stationary structure in fixed relation thereto to form a seal between the wall of said pipe and the wall of the tube.

GEORGE J. STREZYNSKI.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 383,840 Vogel May 29, 1888 2,147,691 Crarnton Feb. 21, 1939 2,302,578 Serrell Nov. 12, 1942 2,435,941 Jones Feb. 10, 1948 2,530,253 Maged et al Nov. 14, 1950 

